57004: 'Category' is empty

This error means the request included Category without a value. Twilio returns this error for Messaging requests when Category is empty or not specified.

• Category was omitted from the request.
• Category was sent as an empty string or blank value.

• Pass a valid, non-empty Category value in the request.
• Validate required fields before sending the request so blank values are rejected earlier. Twilio validates provided parameters and surfaces the exact error, causes, and suggested solutions in error logs.

• Debugging Your Twilio Application
• Programmable Messaging